To achieve adequate profit margins, commercial poultry houses are designed to house large numbers of chickens in compact, densely populated conditions. For example, it is common to house 25,000 chickens in poultry houses measuring 400 by 40 feet. Under these conditions it is essential that the houses be well ventilated and that their air quality and temperature be maintained within proper ranges. To this end poultry houses are constructed with large open windows and equipped with window closures and fans.
As it is not cost efficient for chicken ranchers to monitor poultry house conditions personally on a continuous basis, and to adjust the window closures manually, systems have been devised for automating such activities. For example, in U.S. Pat. No. 3,511,299 one such system is shown which has a motor coupled with cables that control the position of the window closures automatically in response to control signal generated by a thermostat or humidistat. This type of a system however is expensive and requires continuous preventive and corrective maintenance at substantial costs. Also, as this type system uses electric motors, system failure can occur in the event of a power failure or motor failure. Unless this is recognized fairly quickly, system failure can easily lead to a disastrous loss of poultry.
As a result systems have more recently been developed which actuate window closures mechanically without the use of electric motors in the event of power failure. Exemplary of this type of system is that shown in U.S. Pat. No. 3,915,377. This system automatically releases drop curtain type window closures in response to the detection of power failure. Though such does immediately improve cross ventilation, while the house ventilating fans are idled by the power failure, the house air may rapidly become dangerously cold during cold weather conditions. Therefore, here again the rancher himself must still monitor house conditions fairly frequently to avoid injurious conditions from arising even with the use of this type of safety system.
It thus is seen that a need still remains for a system for controlling poultry house window closures on an automated basis that can be operated on a limited basis even during power failure conditions. Accordingly, it is to the provision of such a system that the present invention is primarily directed.